A text document is a flat, sequential structure. It requires that ideas, with all their parts and interrelationships, be woven into a linear thread and packed onto the flat surface of the medium. The author has to lay out scraps of information in a sequential mosaic, while the reader must parse the structure out of the page and visualize in his own mind the author's meaning. The connection between the author and the reader is through a wall of text with little transparency as to any structure or relationship among the ideas.
Prior art systems have employed various means to represent and organize unstructured textual information. Certain note-taking applications blend long-form text with the ability to spatially arrange snippets of text on a two-dimensional canvas. Others group snippets of text into categories which can be searched in various ways. Concept- and cognitive-mapping tools typically eschew long-form text in favor of a graphical representation of information; they model knowledge as a web of simple concepts connected via links. Outliners are a class of note-taking applications that enable the organization of information in hierarchies.
Some outliners allow items to have typed attributes, displayed in columns, giving the effect of a hierarchical table. Spreadsheets may provide means to group rows and columns to form quasi-hierarchical structures that may be collapsed/expanded to hide/show the rows and columns. Certain word processing applications provide tables or grids that may be used to organize textual information.
Certain note-taking and information management tools provide means to link various information items. In various systems relying on flat files as a storage mechanism, links may be created among items residing in the same file. Links across file boundaries are typically implemented via the familiar hyperlink mechanism. Tools relying on a relational database backend may allow semantic links among two or more objects stored anywhere in the database.